FIGS. 7 through 10 show cross-sectional view of a conventional bolt support structure provided to an electrical junction box. Such electrical junction box is mounted to a motor vehicle for supplying electricity and transmitting signals to electronic equipments mounted to the motor vehicle.
The bolt support structure 201 described above includes, as shown in FIG. 7, a bolt 202 having a head portion 220 and a shaft portion 223 and a mount portion 203 to which the head portion 220 is mounted. As shown in FIG. 8, the bolt 202 is arranged to fix a connection portion 40 provided at a bus bar 4 with a connection portion 50 provided at a terminal clamp connected to an end of a power source wire for electrically connecting the connection portion 40 with the connection portion 50. The mount portion 203 is made of synthetic resin and is formed integrally or separately with a frame 211 of the electrical junction box.
For the bolt 202 described above, the head portion 220 is implanted within the resin forming the mount portion 203 such that the shaft portion 223 projects out from an outer surface of the mount portion 203. Furthermore, the bolt 202 is mounted to the mount portion 203 so as to prohibit the bolt 202 from moving with respect to the mount portion 203 in an axial direction of the shaft portion 223.
The bus bar 4 described above is formed by pressing a metallic plate. The bus bar 4 is provided with a plurality of connection portions (not shown) which is electrically connected with an electronic component and the connection portion 40 which is electrically connected with the above-described connection portion 50 of the terminal clamp. This connection portion 40 of the bus bar 4 is formed by bending an end of the bus bar 4 at a right angle and is provided with a through hole 41 through which the shaft portion 223 of the bolt is passed.
The connection portion 50 of the terminal clamp is formed into a flat plate shape and is provided with a through hole 50a through which the shaft portion 223 of the bolt 202 is passed.
Referring to FIG. 8, for the electrical junction box having the above-described bolt support structure 201, first the head portion 220 of the bolt 202 is mounted to the mount portion 203, and then the shaft portion 223 is subjected to sequentially passed through the through hole 41 of the bus bar 4, the through hole 50a of the terminal clamp and a washer 7. Then, a nut 8 is screwed to the shaft portion 223, thereby fixing and electrically connecting the connection portion 40 of the bus bar 4 with the connection portion 50 of the terminal clamp (refer for example to Japan Patent Application Publication H06-276648).
The drawback in the electrical junction box having the above-described bolt support structure 201 is described below. That is, the bus bar 4 is designed to be mounted on the frame 211 of the electrical junction box so that the connection portion 40 of the bus bar 4 is in contact with an outer surface of the mount portion 203; however, in practice, the connection portion 40 may sometimes lift up and detach from the outer surface of the mount portion 203, as shown in FIG. 9. Thus, when the connection portion 50 of the terminal clamp is attached onto this connection portion 40 shown in FIG. 9 and the nut 8 is attached to the shaft portion 223, it causes the connection portion 40 to bend, producing a concentrated stress at a bent portion F. In addition, such concentrated stress on the bent portion F caused by the bending of the connection portion 40 causes a damage to the bus bar 4 as well as defective attachment between the bolt 202 and the nut 8 which is not desirable.